When searching the vault manually, the result is cleared as soon as you leave the Bitwarden pulldown. If the selection remained until you manually leave it or search again, it would be possible to manually C-P both username and password. Under current functionality, you have to search, copy one part, then search again and copy the other, as when going to paste the first part the search is cleared. This would require fewer searches and allow for faster use of Bitwarden in cases where auto detection is not catching the login fields or other issues occur to require manual C-P.
+1 on this - got this functionality in Keeper and it is a time saver and less frustrating.